List of various lithography techniques in the nanometer and micrometer range.
1.1. A laconic antiquity on lithography
Over the last three centuries the term “lithography” (from the ancient Greek
In 1850, the first
|S. No.||Techniques||Patterning methods||Optimum environments||Resolution||Merits||Limits||Examples|
|1.||Microlithography and nanolithography||Creates patterns by structuring material on a fine scale||Vacuum||10 μm and 100 nm||Double/multiple patterning lithography [10, 11]|
|2.||Contact lithography (CL)||Image printed is obtained by illumination of a photomask in direct contact with a substrate coated with an imaging photoresist layer||Vacuum||∼ 100–1000 nm||Fabrication of metal ring arrays on silicon substrate |
|3.||Scanning probe microscope (SPM) lithography||A direct‐write, maskless approach that bypasses the diffraction limit based on tip–sample interaction||Ambient vacuum or liquid phase||Below 50 nm||Micrometer‐scale SPM local oxidation using the micrometer tip under contact‐mode operation |
|4.||Optical photolithography (OPL)||A lithographic printing process that selectively exposes plates or substrate to UV radiation for the formation of images||Vacuum||Usually at sub‐100 nm4||Structures with silver film were used as the exposure mask |
|5.||Electron beam lithography (EBL)||Direct writing of structures down to sub‐10 nm dimensions, and also facilitating high‐volume nanoscale patterning technologies||Vacuum||High resolution up to sub‐10 nm (maximum of ≤50 nm)||Recent developments in processing, tooling, resist and pattern |
|6.||Focused ion beam lithography (FIBL)||Consists of a focused beam of ions that can be operated at low beam currents for imaging or at high beam currents for site‐specific sputtering||Vacuum||≤50 nm||Structuring approaches of novel patterns |
|7.||Extreme ultraviolet lithography (EUVL)||Consists of burning intense beams of ultraviolet light that are reflected from a circuit design (semiconductor integrated circuits (ICs)) pattern into a wafer||High vacuum||≤13.5 nm||Next‐generation semiconductor |
|8.||Light coupling mask nanolithography (LCML)||Consists of a polymer mask placed in contact with the photoresist through transparent regions that protrude through the topographically patterned mask where exposure is required for obtaining the image||Vacuum||≤50–20 nm (365 and 436 nm)||Organic polymers assist amplitude mask for light‐based lithographies |
|9.||X‐ray lithography (XL)||Uses X‐rays to transfer a geometric pattern from a mask to a light‐sensitive chemical photoresist on the substrate||Vacuum||≤20 nm||Lithographic beam lines for soft and hard X‐ray for micro‐ and nanofabrication |
|10.||Nanoimprint lithography (NIL)||Creates patterns by mechanical deformation of imprint resist and subsequent processes||High vacuum or ambient||Resolution up to ∼100 nm||Polymer material (h‐PDMS) |
|11.||Dip‐pen nanolithography (DPN)||Direct‐write patterning technique based on atomic force microscopy (AFM) scanning probe technology on a range of substances with a variety of inks||Vacuum||Minimum resolution up to ∼50 nm||Molecular electronics to materials assembly |
|12.||Neutral atomic beam lithography||Creates patterns by using a neutral atomic beam to create permanent structures on surfaces||Vacuum||∼70 nm||Self‐assembled monolayers of alkanethiolates on Au and alkylsiloxanes on SiO2 |
|13.||Interference lithography||Creates patterns by regular arrays of fine features, without the use of complex optical systems or photomasks||Vacuum||∼50 nm||3D photonic crystals |
|14.||Hot‐embossing lithography||Creates patterns using polymer or glass substrates to imprint structures created on a master stamp||Vacuum||∼50–100 nm||Polymer‐based interdigitated electrodes |
|15.||Creates patterns using rapid photopolymerisation of an entire layer with a flash of UV illumination at microscale resolution; in addition, the mask can control individual pixel light intensity, allowing control of material properties of the fabricated structure with desired spatial distribution||Ambient temperature and atmosphere||∼500 μm||Lincoln Monument |
|16.||Charged‐particle lithography||Used for creating patterns; the imaging action is mediated by charged particles such as electrons (as in EBL) and ions (as in ion beam lithography).||High vacuum or ambient||∼50–100 nm||Fabrication of electronic devices and microstructures using high‐resolution organic resists |
|17.||Neutral‐particle lithography||Used for creating patterns; a broad beam of energetic neutral atoms floods a stencil mask and transmitted beamlets transfer the mask pattern to resist on a substrate||Vacuum||∼50–100 nm||Bird's‐eye view of a 50 nm wide slot |
|18.||Atomic force microscopic nanolithography or scanning force microscopy (SFM)||The simplest way to attain single structure formation in which the tip is immobilised at a specific surface site, and a large force is then applied to the tip to indent the surface||Ultra‐high vacuum (UHV)||∼100 nm||Development of more complex nanodevices such as single‐electron transistors |
|19.||Magneto‐lithography||Creates patterns based on the magnetic field on a substrate, using paramagnetic or diamagnetic masks, that defines the shape and strength of the magnetic field||High vacuum or ambient||∼100 nm||Magnetic Fe3O4 nanoparticles pattern on a gold thin film |
|20.||Multibeam or complementary E‐beam lithography (CEBL)||Uses multiple miniature columns and vector scanning of shaped beams (critical layers) to boost throughput||UHV||∼50–100 nm||Development of more complex nanodevices |
|21.||Scattering with angular limitation in projection electron beam lithography (SCALPEL)||Creates patterns with extremely small features in microelectronic circuits. Electrons are projected onto a “mask”, which then pass straight through the mask, transferring the image of the mask to the wafer||UHV||∼70 nm||For semiconductor manufacturing lithography with feature sizes beyond the capabilities of optical lithography |
2. Next‐generation lithography in the new skylines of science and engineering
Fabrication on micro‐ and nanoarchitectures has opened new horizons in the area of engineering, science and technology. The success of improving and yielding micro‐ and nanodevices and integrated circuits (ICs) by using photolithography practices is prominently incredible. Nanofabrication is considered as a “gating” technology for the accomplishment of all future advanced nanodevices. Over the past two decades, photolithography had been broadly used for the purpose of microdevices and integrated circuit (IC) technology. However, the wavelength of photons and the search for optics and resistance offered by the materials have limited the resolution of nanostructures prepared from lithography to about 100 nm. In addition, next‐generation lithography (NGL) processes, such as maskless, E‐beam and direct write lithography, require specific and expert intervention to open up new product/market combinations. The movement towards 450 mm wafers presents its own set of challenges. The larger wafers require new processes, and equipment cost control is a key concern. The equipment needed to support these techniques needs to be as precise and reliable as the chips they make. There are five important candidates for NGL  technology to ensure rigorous growth: (1) X‐ray proximity, (2) extreme ultraviolet lithography (EUV), (3) ion projection lithography (IPL), (4) scattering with angular limitation projection electron‐beam lithography (SCALPEL), and (5) nanoimprint lithography (NIL). NGL technology would be familiarised and alike adept for the probable imminent in a mix‐and‐match mode along with optical lithography. Continuing developments based on NIL are leading semiconductor manufacturers to use this technological development as a probable auxiliary for optical lithography, but which may be limiting due to its reduced capacity [33, 34]. As a consequence, the existing tumult in the fabrication of novel technological developments is associated with the development of innovative thoughts on the emerging field of nanotechnology, high‐power LEDs, nano/micro‐ICs and so on. A maskless NGL tool could meet the following requirements: cycle time, mask cost, removal of the mask input to the compact disk (CD) control, etc. With a comparable industrial price for numerous wafers per mask, there would be a need for this NGL implement by means of no issue whether the manufactured goods is logic, flash, or Dynamic Random Access Memory (DRAM). This trend continues uninterrupted. As followed by Moore’s law, it is required to follow the incessant progressions in lithographic steadfastness.
In light of the aforementioned discussion, lithography has shown that, with high novel scientific achievements and research, it may outshine other innovative applications for the purpose of common interest. Among the major notable growth areas are the diverse fields of nanotechnology, photovoltaics/solar cells, displays, LEDs and eco‐friendly materials. Differences in innovative lithographic printing techniques continue to be improved through novel global progressions in spectral imaging, time‐correlated single‐photon counting, noninvasive optical biopsy, visual implants and kinetic chemical reaction rates. Hence, research on exclusive lithographic printing technological accomplishments would lead the way to more effective techniques, while coating thin films at the atomic level may turn out to be the ideal printing technology for the future.
The authors apologise for inadvertent omission of any pertinent references.
Conflict of interest
The authors declare that there is no conflict of interest related to the publication of this chapter.